Isolation,Identification And Fermentation Charateristics Of Wine Yeast In Hebei Province

Yeast is the main factor to produce flavor substances related to the sensory characteristics of wine.Over the years,the yeasts used in China ’s wineries are all imported commercial yeasts,resulting in the lack of personality and characteristics of domestic wines.Therefore,the isolation of characteristic wild yeasts from grapes has become a trend,which has a profound impact on the breeding of local characteristic yeast strains in China.In this experiment,six kinds of grape fruits of ’ Xila ’,’ Longan ’,’Cabernet Sauvignon ’,’ Marselan ’,’ Merlot ’ and ’ Cabernet Gernischt ’ in Qinhuangdao City,Huailai County and Zhuolu County of Zhangjiakou City,Hebei Province were picked.The yeasts on the surface of the fruits were isolated,and a total of 323 strains with obvious yeast characteristics were obtained.Using the colony characteristics of yeast strains on WL medium for classification and identification,all yeasts can be divided into 10 categories,9 categories of wild yeasts and an unknown strain that cannot be identified according to the literature.They were Saccharomyces cerevisiae,Torulaspora delbrueckii,Hanseniaspora uvarum,Zygosaccharomyces rouxii,Schizosaccharomyces pombe,Rhodotorula,Pichia membranae,Pichia kluyveri,Issatchenkia orientalis and unknown yeast.The fermentation ability of 323 strains of yeast was determined by Durham tube fermentation,and 3 strains were screened from each yeast,a total of 30 strains with strong fermentation ability.The glucose tolerance,ethanol tolerance,acidity tolerance,sulfur dioxide tolerance and temperature tolerance were measured by spectrophotometry.The results showed that 10 wild yeasts were the most tolerant and had the potential to be excellent yeasts.They were commercial yeast Angel,LADE and wild yeasts HSX10,HSX9,QM24,QC16,QS8,QC27,QS7,Z1L11,HSC23,HIC19.With Angel and LADE commercial yeast as the control,small tank fermentation was carried out with the screened wild yeast,and its physical and chemical properties were determined for sensory evaluation.The results showed that the chromaticity value and alcohol value of HSX10 were higher than those of commercial yeast Angel.The total acidity and residual sugar content were slightly lower,and the sensory evaluation was only 2.8 points compared with Angel.Five yeast strains including Angel yeast(HSX10,HSX9,QM24,QC27,QC16,Angel)were selected for the determination of volatile substances.The volatile substances were determined by GC-MS mass spectrometry,and 22 kinds of alcohols,23 kinds of esters and 24 kinds of other substances were detected in the fermentation products of wild yeast.Based on the tolerance,fermentation ability and aroma-producing properties of yeast,through literature review and comparison with commercial yeast,the local yeast with excellent fermentation characteristics with the highest sensory score of HSX10 was finally selected.